The present invention relates to a vehicle braking system. It finds particular application in conjunction with an anti-lock braking system and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
Heavy vehicle braking systems commonly rely on compressed air for operating a vehicle braking system. Compressed air is produced by a compressor and stored in at least one reservoir. Various valves control fluid communication between the at least one reservoir and various brake circuits and individual brake chambers on respective wheels. Opening a valve from a reservoir to a brake circuit or a brake chamber increases the volume available for the compressed air stored in the reservoir. If an increased volume is available for the same amount of compressed air, the pressure of the compressed air in the increased volume drops.
In general, an anti-lock braking system (ABS) applies, holds, and releases pressure at an individual brake or multiple brakes to improve traction of the associated wheel and, furthermore, enhance vehicle control. Applying, holding, and releasing an individual brake is achieved by actuating and deactuating a valve associated with that brake. As discussed above, if the valve is in the apply state, the volume available for the compressed air increases, thereby decreasing the pressure in the reservoir. Decreased pressure in a brake circuit may impact the braking torque available to other brake chambers in the circuit.
The present invention provides a new and improved apparatus and method for addressing a decreased pressure available to brake chambers in a circuit when a valve to one of the brake chambers is in the apply state.